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Fiddling with my first Matter device - 10A 1CH switch [CB3S / BL2028N (BK7231N)]

divadiow 
I grabbed this from Ali to have a play. https://www.aliexpress.com/item/1005006155824101.html

Image of an AliExpress product page showing the Matter1CH switch module.

It comes with a CB3S module which is BK7231N.

The VCC was just about accessible with a pin, so no soldering.

Short boot log:


BK7231n_1.0.13
REG:cpsr        spsr        r13         r14
SVC:0x000000D3              0x00401C1C  0x000033AC
IRQ:0x000000D2  0x00000010  0x00401E0C  0x37A60330  
FIR:0x000000D1  0x00000010  0x00401FFC  0x7A05E227  
SYS:0x000000DF              0x0040192C  0x00000158  
ST:0x00000000
[I/FAL] Fal(V0.4.0)success


go os_addr(0x10000)..........



Assuming the CB3S module was standard hardware I used BKflasher to dump the factory firmware, attached. I also took a small risk and flashed OBK to the module to see if it would boot up with an AP, as expected with any non-Matter BK device, but sadly not. I was able to flash it back to factory though and it worked again.

Will OBK not working be because of some other partition differences? The RF partition? Should I try "Restore RF part" in the easy flasher?

Will OBK support Matter one day? Does it need to? I know there's a lot of other development, so maybe low priority.

Questions!

Anyway, here are some more pics

Matter 1CH switch module next to an open casing with a visible electronic board on a green measurement mat. Electronic module with visible components labeled RSH-2L-TDQ001-WiFi-V1.0 Close-up of a PCB with various electronic components, including a KP16051SF chip. Smart module with casing and box. CB3S module with electronic components on a green mat. Electronic module with a green terminal block and a black relay. Relay module on a wooden surface. CB3S electronic module mounted on a board with other components. Confirmation of Uascent smart plug connection with Alexa account.
Screen of BK7231 Easy UART Flasher app showing successful write process.

About Author
divadiow
divadiow wrote 2742 posts with rating 470 , helped 245 times. Live in city Bristol. Been with us since 2023 year.

Comments

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p.kaczmarek2 02 Feb 2024 09:39

That's a very interesting and informative post. I haven't seen a matter BK7231 yet. Are you really sure that's BK7231N inside and not a BK7231M? Since you're saying it's not booting, did you try... [Read more]

divadiow 02 Feb 2024 11:56

interesting. I had not heard of BK7231M. After spending ages flashing various CB3S and other BK7231N firmware, and even the BK7231M firmware from https://www.elektroda.com/rtvforum/viewtopic.php?p=20837165#20837165 I... [Read more]

p.kaczmarek2 02 Feb 2024 12:04

That's very strange, BL2028N is known to work with OpenBeken. Have you tried flashing whole 2MB of dump from a working OBK device or a flashable Tuya device? I would say that it has to work, because... [Read more]

divadiow 02 Feb 2024 12:26

yeh weird. I'll flash again with OBK and leave it longer. [Read more]

p.kaczmarek2 02 Feb 2024 12:52

I've searched for 0x00401C1C , here is a possibly related thread: Flashing Aubess Plug via Serial Adapter: BK7231M/CB2S Not Creating Open AP Post-Flash That seem to confirm that you have the M flavour... [Read more]

divadiow 02 Feb 2024 20:59

yes, quite a few now. some of my own and at least these two in repo. no AP or log out with any https://obrazki.elektroda.pl/3295173900_1706896095_thumb.jpg do we have any full 2mb ones from... [Read more]

p.kaczmarek2 03 Feb 2024 07:49

I have some BK7231M devices sent by a user. Currently I've checked the dumps and they seem to have changed encryption keys, so the solution would be to build OBK with a correct keys: https://obraz... [Read more]

divadiow 03 Feb 2024 09:15

to add the public discourse the shield over the Belon has these markings - UAM028 https://obrazki.elektroda.pl/7019581100_1706947096_thumb.jpg which suggests these are not Tuya, but uHome.... [Read more]

p.kaczmarek2 03 Feb 2024 09:22

What is the MAC address of this device? Added after 24 : EDIT: Wait it seems you posted the reply on the screenshot while I was posting my question [Read more]

divadiow 03 Feb 2024 09:25

ha. thought you'd gone mad 38:73:EA:E2:C5:8B yes [Read more]

divadiow 17 Feb 2024 18:09

I picked up another Matter device. The familiar 16A mini switch. To my surprise this one comes with an ESP32-C3 chip on module SM-028C3 on a little riser. I can only find this in relation to that module... [Read more]

ferbulous 19 Feb 2024 08:44

Hi @divadiow How did you restore to the stock firmware for the BL chip? [Read more]

divadiow 19 Feb 2024 09:13

oh. I think I used the Easy flasher. You have to check the "allow backup restore" box https://obrazki.elektroda.pl/8944725900_1708330279_thumb.jpg and I think the filename has to start "readResult_BK7231N_QIO.."... [Read more]

ferbulous 19 Feb 2024 09:19

Thanks, i actually tried to restore to stock using bk7231tools but never worked for me. This was before easy launcher tool though Do you plan to swap esp32c3 chip on the matter relay switch since it’s... [Read more]

divadiow 19 Feb 2024 09:32

excellent. well. I don't *need* to, I have it just to play with tbh. I've got quite a few smart switches now. I am playing with a tiny ESP8285 that was orphaned from a destroyed GU10 that I've... [Read more]

ferbulous 19 Feb 2024 09:44

Any WB2S/CB2S should be a drop in replacement Or this esp32c2 module https://m.intl.taobao.com/detail/detail.html?id=717948565081 [Read more]

divadiow 19 Feb 2024 09:51

sure. a module would be much nicer than squeezing in something hacky. though it'd be more about the challenge than ending up with a working/deployable device. [Read more]

ferbulous 19 Feb 2024 10:09

Not quite, but I do have a similar relay device like the matter version you have but it’s using TR6260 chip. I swapped it for esp32c2 running tasmota [Read more]

divadiow 19 Feb 2024 10:22

ah yes. i see https://www.elektroda.com/rtvforum/topic3965929.html [Read more]